The present invention relates to high speed weaving machines or looms, and more particularly to the heddle frames used in such high speed weaving machines.
Typically, heddle frames used in high speed weaving looms comprise a pair of end braces configured with a pair of laterally extending rails or slats. The connection between the end braces and slats is critical for proper operation of the weaving machines and has been a source of persistent problems in the field. In the past, the end braces have been rigidly attached to the top and bottom of the slates. The end braces were then free to slide in a guiding groove on a support of the weaving machine to form a shed during weaving operations. With the advent of high speed weaving machines, which may make as many as six hundred or more sheds per minute, the reciprocating motion of the heddle frame was very rapid and the inertia of the heddle frame, owing to its weight, was very great. This caused frequent breaking of the heddle frames, particularly at the connection between the end braces and top and bottom slats.
Conventionally, the top and bottom slats of the heddle frame have been made of lightweight hollow aluminum beams. The end braces are then fitted to the hollow aluminum beams. However, the aluminum slats or rails are subjective to a substantial amount of bending which exerts a flexing movement on the connection between the end braces and the slats. This flexing action results in fatigue of the components comprising the connection between the end braces and the slats, thereby causing frequent failure of the heddle frames.
Several attempts have been made to provide improved heddle frames. For example, U.S. Pat. No. 4,750,526 describes a quick release connection provided between the end braces and the laterally extending cross rails. This device utilizes a connector which is fixed within an opening in the cross rail having means for compressively gripping a projection which extends at a right angle from the end brace.
Another attempt to overcome the problems with conventional heddle frames is shown in U.S. Pat. No. 4,022,252. In this patent, the end brace has a metal core, a portion of which is covered with plastic to provide additional strength. A pair of joining pieces project from the strengthened portion of the core of the end brace as one body and form a tapered groove there between. These projections extend into the hollow body of the cross rail. The end brace is anchored to the cross rails by means of a wedge shaped member which is attached to the end brace by screws. The wedge shaped member enters the tapered groove formed by the projecting pieces so as to force the projecting pieces against the side walls of the cross rail, thereby locking the end brace firmly to the cross rail.
U.S. Pat. No. 4,230,159 describes a heddle frame wherein the end brace is joined to the cross rail by means of a plastic projection which extends into the hollow space of the cross rail and is pinned to the cross rail by a single pin which permits the projection to pivot about the pin thereby providing a flexible joint. A packing material is packed in the space between the end brace and across rail. This device permits flexibility of the joint but cannot be readily disassembled for drawing in of the work yarns or for replacement of component parts.
Thus, although a number of attempts have been made to provide a more reliable connection between the end brace and cross rails, such connections have only been achieved through relatively complicated and not easily disassembled connecting assemblies which do not provide adequate strength for the frame. For example, conventional connecting screws that extend through the end brace in a parallel or perpendicular direction tend to create relatively high stress points which are susceptible to failure in a relatively short time. Additionally, the location of drive elements on modern weaving machines overlaps and thereby prevents the use of several existing screw locations of conventional connecting assemblies.
The present invention provides a quick change end brace connection having extremely high fatigue resistance that eliminates the known disadvantages as discussed above.